1. Field of the Invention
The present invention relates generally to techniques for performing wellsite operations. More specifically, the present invention relates to techniques for sampling fluid at a production wellsite.
2. Background of the Related Art
Oil rigs are positioned at wellsites for performing a variety of oilfield operations, such as drilling a wellbore, performing downhole testing and producing located hydrocarbons. Downhole drilling tools are advanced into the earth from a surface rig to form a wellbore. Drilling muds are often pumped into the wellbore as the drilling tool advances into the earth. The drilling muds may be used, for example, to remove cuttings, to cool a drill bit at the end of the drilling tool and/or to provide a protective lining along a wall of the wellbore. During or after drilling, a tubular may be cemented into place to line at least a portion of the wellbore. Once the wellbore is formed, production tools may be positioned about the wellbore to draw fluid to the surface.
During wellsite operations, it may be desirable to obtain downhole fluid samples to determine various parameters of the wellsite. Techniques for sampling are described, for example, in U.S. Patent Nos. 2008/0135239, 6,467,544, 6,659,177, and 7,243,536. In some cases, the fluid may be separated during sampling as described, for example, in U.S. Patent/Application Nos. 7,434,694, 20080115469 and 20100059221. In some other cases, fluid may be sampled in zproduction or subsea operations as described, for example, in U.S. Patent/Application Nos. 2010/0058221, 2011/0005765, 2009/028836, and 6,435,279, and in PCT Application Nos. WO2010/106499, and WO2010/106500.
Despite the development of techniques for sampling, there remains a need to provide advanced techniques for sampling wellsite fluid. It is desirable that such measurements maintain the quality of the sample as it is collected and retrieved. The invention contained herein is directed at achieving these advanced techniques.